How to Replace Shed Roof Felt

Old shed felt goes brittle, splits at the ridge, and lifts at the eaves until every shower drips onto tools below. Replacing shed roof felt only works if you strip the old layer cleanly and fix soft boards before you trap damp under a shiny new skin.

New-build felting on fresh boards: how to felt a shed roof. Project hub: how to build a garden shed. If walls are still going up, finish assembly first.

Is it a felt job or a timber job?

Press a screwdriver into suspect boards. If it sinks easily, cut out and replace that section with matching thickness board. Felting over cardboard-soft OSB wastes a weekend.

Ladder and height: Stripping felt means leverage and sudden tears. Keep the ladder footed, work one section at a time, and do not stand on boards you have just found to be rotten. Wear gloves; old felt and rusty clouts cut. If the roof feels unsafe, stop and get a carpenter rather than improvising from a wobbly perch.

No torch-on work and no electrical steps here.

Strip and replace kit

Step-by-step

1. Clear the roof and strip the old felt

Empty shelves under the work area if drips or debris will fall inside. Starting at a verge or ridge, prise up the old felt and pull clout nails as you go. Work in calm weather; half-stripped roofs hate wind. Bag the waste as you strip so it does not blow around the garden.

2. Inspect and repair the deck

With the boards bare, look for dark staining, sprung joints, and nail holes clustered into broken edges. Replace rotten boards. Punch remaining nail stubs flush or remove them. Sweep grit off; grit under new felt wears holes from the underside. If purlins are rotten where they meet the walls, fix those before you close the roof again.

3. Let wet timber dry (or swap it)

If boards are damp but sound, give them a dry day or two with the roof open under a temporary tarp that still vents. Do not seal soaking timber under new felt. Boards that stay dark and soft after drying need replacing, not wishing.

4. Refelt as on a new roof

Lay new mineral felt from the eaves upward with proper overlaps, tight nailing at edges, and a proper ridge cover. Sequence and overlaps match the new-roof guide: how to felt a shed roof. Turn down eaves and verges cleanly. Refit ridge rails or barge details that came off during stripping.

5. Check inside after the first rain

Look for dark lines at board joints and drips at the ridge. Small misses are easier to lift and re-nail in the first week than after the felt hardens into shape.

Mistakes that bring the leak back

• Nailing new felt straight over old felt “as a second skin”. You double the weight, hide rot, and create air pockets that flap.
• Leaving a forest of old clouts proud so they spear the new layer from below.
• Refelting while the boards are still wet from the last storm.
• Skipping the ridge strip because the old one had vanished years ago.

When to call a carpenter

Call help if more than a board or two is rotten, if the roof structure has spread, or if the shed has racked so the ridge is twisted. A full re-board plus felt on a tall building may need scaffold. Soft corners in the walls often mean a bigger repair than a felt renew. Floor leaks after roof work can point lower down: build a garden shed base.

Related: felt a shed roof, fit shed windows and doors, build a garden shed, build a garden shed base.

FAQ

Can I put new shed felt over old felt?

It is a poor fix. Strip the old layer so you can see the boards and nail into solid timber. Overfelting hides rot and rarely sits flat.

How often should shed roof felt be replaced?

In UK weather, budget for inspection every few years and replacement when cracks, bald patches, or lifted edges appear. Cheap felt on a south-facing roof can fail in under a decade; heavier felt lasts longer if nailed well.

Why does my shed still leak after new felt?

Usually a missed overlap, a punctured board edge, a ridge without a proper cap, or water entering at a window or door head rather than through the field of the roof. Check those junctions next.